A TAB (tape automated bonding) technique is known as one of IC chip mounting techniques. In the TAB technique it is possible to form leads with many pins and narrow pitch as compared with the other mounting techniques, and high-speed automatic bonding is applicable to the IC chip with its face-up. Therefore, the TAB technique has especially been highlighted in recent years.
A TAB tape has a structure in which one or more IC chips can be mounted on each package on a film carrier including a film of synthetic resin such as polyimide and leads formed thereon. The leads include those which extend outside the package are to be connected to a mounting substrate and others which extend in the package for interconnection within one IC chip or interconnection among a plurality of IC chips. The bondings of those leads to the IC chip are usually made by a transfer bump system in which the leads and electrodes of the IC chip are bonded through pressing and heating with bumps preformed by transfer at end portions of the leads of the film carrier.
JP-A-(Sho)59-54252 discloses a plurality of IC chips mounted on one package. According to the disclosure, wirings are preformed on a TAB tape in order to accommodate two IC chips in one package. However, it is required that the IC chips to be accommodated in the package are designed so that no jumper wiring is required between the chips. In the case where cross wirings between IC chips are inevitable, it is impossible to make the wirings by use of only leads formed on the film carrier. In that case, it may be considered to form leads on opposite surfaces of the film, form through-holes in the film at predetermined positions, and make electrical connection between the leads on the opposite surfaces of the film through the through-holes. In a multi-pin, narrow-pitch TAB tape, however, this method involves problems since the formation of through-holes is difficult and the cost is increased. Therefore, in the conventional semiconductor device, it was necessary to make the cross wirings outside the package. A primary purpose of accommodation of a plurality of IC chips in one package is to save a space for an electronic circuit system. Accordingly, the provision of the cross wirings outside the package reduces the merit of accommodation of a plurality of IC chips in one package since a space occupied by the cross wirings is additionally required and this space is increased as the number of cross wirings becomes large. There are further problems including poor the outward appearance and the higher possibility of disconnection and/or short circuit occurring in the cross wirings, resulting in less reliability of an equipment in which the package is used.
The present invention has been made under the above circumstance and has an object to provide a semiconductor device in which connections between electrodes of each semiconductor element and between semiconductor elements are possible in one package and a substrate which is a part of the semiconductor device and used for assemblage of such a semiconductor device.